Bottom portion of a lamp



FIG. 1 is a perspective view of a bottom portion of a lamp in accordance with the present design;

FIG. 2 is a front view thereof, the rear view being a mirror image;

FIG. 3 is a right view thereof, the left view being a mirror image;

FIG. 4 is a bottom view thereof; and,

FIG. 5 is a top view thereof.

The broken lines are for illustrative purposes only and form no part of the claimed design. Any shading forms no part of the claimed design and is provided to illustrate contour only and is not an indication of texture, gloss, and the like. 

CLAIM The ornamental design for a bottom portion of a lamp, as shown and described. 